Question

我试图分别通过两个不同的按钮打开两个活动，但是当我运行我的应用程序时，应用程序立即崩溃。请帮助我对android编程了解不多。

这是我的活动代码，其中两个按钮都是：

net.masterthought.cucumber.ValidationException: Passed files have no features!
    at net.masterthought.cucumber.ReportParser.parseJsonFiles(ReportParser.java:78)
    at net.masterthought.cucumber.ReportBuilder.generateReports(ReportBuilder.java:88)
    at net.masterthought.jenkins.CucumberReportPublisher.generateReport(CucumberReportPublisher.java:419)
    at net.masterthought.jenkins.CucumberReportPublisher.perform(CucumberReportPublisher.java:336)
    at hudson.tasks.BuildStepCompatibilityLayer.perform(BuildStepCompatibilityLayer.java:79)
    at hudson.tasks.BuildStepMonitor$1.perform(BuildStepMonitor.java:20)
    at hudson.model.AbstractBuild$AbstractBuildExecution.perform(AbstractBuild.java:741)
    at hudson.model.AbstractBuild$AbstractBuildExecution.performAllBuildSteps(AbstractBuild.java:690)
    at hudson.maven.MavenModuleSetBuild$MavenModuleSetBuildExecution.post2(MavenModuleSetBuild.java:1074)
    at hudson.model.AbstractBuild$AbstractBuildExecution.post(AbstractBuild.java:635)
    at hudson.model.Run.execute(Run.java:1840)
    at hudson.maven.MavenModuleSetBuild.run(MavenModuleSetBuild.java:543)
    at hudson.model.ResourceController.execute(ResourceController.java:97)
    at hudson.model.Executor.run(Executor.java:429)

这是日志猫：

2019-09-20 15：06：48.417 4196-4196 / com.example.splash E / AndroidRuntime：FATAL EXCEPTION：main 流程：com.example.splash，PID：4196 java.lang.RuntimeException：无法启动活动ComponentInfo {com.example.splash / com.example.splash.ActivityB}：java.lang.NullPointerException：尝试调用虚拟方法'void android.widget.Button.setOnClickListener（android。 view.View $ OnClickListener）'上的空对象引用在android.app.ActivityThread.performLaunchActivity（ActivityThread.java:3121）在android.app.ActivityThread.handleLaunchActivity（ActivityThread.java:3260）在android.app.servertransaction.LaunchActivityItem.execute（LaunchActivityItem.java:78）在android.app.servertransaction.TransactionExecutor.executeCallbacks（TransactionExecutor.java:108）在android.app.servertransaction.TransactionExecutor.execute（TransactionExecutor.java:68）在android.app.ActivityThread $ H.handleMessage（ActivityThread.java:1976）在android.os.Handler.dispatchMessage（Handler.java:106）在android.os.Looper.loop（Looper.java:193）在android.app.ActivityThread.main（ActivityThread.java:6912）在java.lang.reflect.Method.invoke（本机方法）在com.android.internal.os.RuntimeInit $ MethodAndArgsCaller.run（RuntimeInit.java:493）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:860）原因：java.lang.NullPointerException：尝试在空对象引用上调用虚拟方法'void android.widget.Button.setOnClickListener（android.view.View $ OnClickListener）' 在com.example.splash.ActivityB.onCreate（ActivityB.java:42）在android.app.Activity.performCreate（Activity.java:7144）在android.app.Activity.performCreate（Activity.java:7135）在android.app.Instrumentation.callActivityOnCreate（Instrumentation.java:1293）在android.app.ActivityThread.performLaunchActivity（ActivityThread.java:3101）在android.app.ActivityThread.handleLaunchActivity（ActivityThread.java:3260）在android.app.servertransaction.LaunchActivityItem.execute（LaunchActivityItem.java:78）在android.app.servertransaction.TransactionExecutor.executeCallbacks（TransactionExecutor.java:108）在android.app.servertransaction.TransactionExecutor.execute（TransactionExecutor.java:68）在android.app.ActivityThread $ H.handleMessage（ActivityThread.java:1976）在android.os.Handler.dispatchMessage（Handler.java:106）在android.os.Looper.loop（Looper.java:193）在android.app.ActivityThread.main（ActivityThread.java:6912）在java.lang.reflect.Method.invoke（本机方法）在com.android.internal.os.RuntimeInit $ MethodAndArgsCaller.run（RuntimeInit.java:493）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:860）

这是activity_b.xml：

  @Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_b);
    video1=(VideoView)findViewById(R.id.video1);
    b1=(Button)findViewById(R.id.button);
    b2=(Button)findViewById(R.id.button2) ;
    Uri u=Uri.parse("android.resource://"+getPackageName()+"/"+R.raw.video2);
    video1.setVideoURI(u);
    video1.start();
    video1.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {
        @Override
        public void onPrepared(MediaPlayer mediaPlayer) {
            mediaPlayer.setLooping(true);
        }

    });
    b2.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            startActivity(new Intent(ActivityB.this,LoginPage.class));
            overridePendingTransition(R.anim.fadein,R.anim.fadeout);
        }
    });
    b1.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            startActivity(new Intent(ActivityB.this,login.class));
            overridePendingTransition(R.anim.fadein,R.anim.fadeout);
        }
    });

}

Answer 1

b1=(Button)findViewById(R.id.botton);

应该是：

b1=(Button)findViewById(R.id.button);

由于b1为空，因为未识别R.id.botton，因此当您尝试将点击监听器附加到该空指针时，会抛出空指针。

为什么在使用onclicklistener时我的应用程序崩溃了？

1 个答案: